Danny Welbeck grabbed the first hat-trick of his career as Arsenal got their Champions League campaign back on track by thrashing Galatasaray 4-1.

Welbeck opened the scoring with his first goal at the Emirates since his £16m move from Manchester United and then added two more, with Alexis Sanchez also on target.

Even the sending-off of goalkeeper Wojciech Szczesny with half an hour remaining could not sour the night for the Gunners, who are now up and running in Group D after recording their biggest win in the competition for four years.

Arsenal dominated from the first whistle, with Welbeck, Sanchez and Mesut Ozil repeatedly punching holes in the Turks’ defence but initially creating few clear chances.

Kieran Gibbs almost opened the scoring, arriving late to meet Alex Oxlade-Chamberlain’s cross at the far post, but the ball was deflected behind.

However, the Gunners finally broke the deadlock midway through the first half as Gibbs found Sanchez darting into space and the Chilean sent a perfect through ball towards Welbeck, who stabbed it under goalkeeper Fernando Muslera.

What little defensive solidity the visitors had shown quickly evaporated and Sanchez took advantage, making room inside the box but dragging his shot wide.

Welbeck doubled Arsenal’s lead on the half-hour, pouncing on a stray Galatasaray header and outpacing Felipe Melo to fire his second past Muslera.

The striker might have completed his treble when Ozil teed him up soon afterwards, but this time Muslera made the save – while, at the other end, Szczesny was awoken from his slumbers to stop a shot on the turn from Goran Pandev.

Normal service was soon resumed, though, and Sanchez made it 3-0 five minutes from the break, collecting Ozil’s pass and turning Aurelien Chedjou before finding the bottom corner.

And any hopes the Turks might have harboured of a dramatic fightback were extinguished when Welbeck completed his hat-trick seven minutes into the second half.

The former Manchester United man was involved at the outset of the move, playing the ball inside to Santi Cazorla and then regaining it, via Oxlade-Chamberlain, to clip a confident finish past the keeper.

It looked as if nothing could go wrong for Arsenal until, out of nowhere, they gave the ball away in midfield and Burak Yilmaz sped through, only to be felled by Szczesny.

Referee Ginaluca Rocchi showed the goalkeeper a straight red card and David Ospina was rushed into the fray, but his first act was to retrieve the resulting Yilmaz penalty from the back of the net.

Inevitably, the Gunners’ momentum was halted, and Ospina had to fling himself to his right to keep out a Yilmaz header, while Wesley Sneijder also tested the substitute keeper.

But it was Arsenal’s night and Cazorla might even have added a fifth goal in injury time, collecting Jack Wilshere’s pass and chipping Muslera, but Semih Kaya scrambled the ball off the line.

Arsenal: Szczesny; Chambers, Mertesacker, Koscielny, Gibbs; Flamini; Oxlade-Chamberlain (Rosicky 68), Cazorla, Ozil (Wilshere 77), Sanchez (Ospina 62); Welbeck.